At the beginning of the third millennium the concern of people everywhere is increasingly on sustainability. As people realise that fossil fuels are a finite energy resource, the search for renewable, clean energy sources has become more urgent. Global warming and climate change have focussed attention on the need to reduce our dependence on fossil fuels. One of the most promising renewable energy sources is wave energy. It has been estimated that the worldwide energy potential of wave power is 2 Terawatts, which is equivalent to a worldwide resource of about 2000 TWh per year—sufficient for much of the world's electrical energy requirements. Although there has been a desire to harness the energy of waves for hundreds of years, past attempts have met with limited success. The successes have been on a small scale, in the order of tens to hundreds of kilowatts rather than the hundreds of megawatts required.
One of the major difficulties in the past has been to design a unit that is sufficiently robust to withstand the enormous power that is possessed by the ocean's waves. In storm conditions the wave energy can be massive, causing the destruction of many of the prior art land- or shore-based systems. The typical prior art approach to extracting wave energy has been to use a turbine or hydraulic system. There have been some attempts to use a directly driven rotary generator, as well as a directly driven linear generator. However the most common prior art energy extraction units are oscillating water columns and hydraulic linked rotary generators. These are typically used in near-shore, in-shore or on-shore installations. Another major drawback of such prior art systems is the need to be close to shore where the energy loss for shoreline waves is high due to frictional losses, thus missing out on the majority of the wave energy present in ‘deep’ water.
The present invention was developed with a view to providing a tension mooring system and a wave energy converter that can be used either near-shore or offshore to extract a maximum amount of ocean wave energy.
References to prior art in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.